volcanic explosivity index

An index published in 1982 by Christopher Newhall and Stephen Self, for rating the explosivity of volcanic eruptions.1  Acronym, VEI.

Criteria1 VEI
0 1 2 3 4 5 6 7 8
Description non-explosive small moderate moderate to large large very large
Volume of ejecta
(cubic meters)
<104 104
106
106
107
107
108
108
109
109
1010
1010
1011
1011
1012
>1012
Tsuya class2 I II-III IV V VI VII VIII IX
Column height
(kilometers)3
<0.1 0.1-1 1-5 3-15 10-25 >25
Qualitative
description
gentle, effusive explosive cataclysmic, paroxysmal, colossal
      severe, violent, terrific
Classifications   Strombolian   Plinian
Hawaiian Vulcanian Ultraplinian
Duration of
continuous blast (hours)
<1   >12
    1-6        
      6-12      
CAVW maximum explosivity4 lava flows explosion or nuée ardente
  phreatic      
dome or mudflow              
Tropospheric injection negligible minor moderate substantial
Stratospheric injection none none none possible definite significant

After Newhall and Self.

1. Christopher G. Newhall and Stephen Self.
The volcanic explosivity index (VEI): An estimate of explosive magnitude for historical volcanism.
Journal of Geophysical Research, volume 87 number C2, pages 1231-1238 (20 February 1982).

notes on criteria

1. Criteria are listed in decreasing order of reliability.

2. Tsuya classification (based on volume of ejecta), assuming pyroclastic flows.  The scale is defined in:

H. Tsuya.
Geological and petrological studies of volcano Fuji, 5.
Tokyo Daigaku Jishin Kenkyusho Iho, volume 33, pages 3-382 (1955).

3. For VEI's 0 – 2, measured from the crater rim; for VEI's 3 – 8, measured from sea level.

4. Most explosive activity indicated for the eruption in the Catalog of Active Volcanoes of the World.

Some Examples of VEI Ratings

Volcano Date of Eruption VEI
Kilauea,
Hawaii, U.S.
almost continuous 0
Nyiragongo,
Dem. Rep. of Congo
began 17 January 2002 1
Soufriere Hills,
Montserrat
began 18 July 1995 3
Eyjafyallajökull,
Iceland
2010 4
Mt. St. Helens
U.S.
18 May 1980 5
Mt. St Helens,
U.S.
1540 ± 70 5
Krakatau,
Indonesia
26 Aug 1883 6
Tambora,
Indonesia
5 April 1815 7
Samalas,
Indonesia
1257 7
Yellowstone,
U.S.
1.3 million years ago,
2.8 × 1011
7
Yellowstone,
U.S.
630,000 years ago,
1 × 1012
8
Yellowstone,
U.S.
2 million years ago,
2.5 × 1012
8

Note: Because of the open-ended nature of the scale, for the Yellowstone eruptions we have provided the volume of ejecta in cubic meters as estimated by the U.S. Geological Survey.

home | units index | search |  to email Sizes drawing of envelope |  acknowledgements | 
help | privacy | terms of use